Rousseau's Savoyard Vicar makes creative use of Descartes's meditative method by applying it to practical life. This ?misuse? of the Cartesian method highlights the limits of the thinking thing as a ground for morality. Taking practical philosophy as first philosophy, the Vicar finds bedrock certainty of the self as an agent in the world and of moral truths while distancing himself from Cartesian positions on the distinction, union and interaction of mind and body. Rousseau's Moral Letters harmonize with the Vicar's view. Descartes would reject the Vicar's appropriation, as real-life problems cannot wait on meditation to answer them